1. ConcepTest 4.1aNewton’s First Law I ConcepTest 4.1a Newton’s First Law I 1) there is a net force but the book has too much inertia 2) there are no forces acting on it at all 3) it does move, but too slowly to be seen 4) there is no net force on the book 5) there is a net force, but the book is too heavy to move A book is lying at rest on a table. The book will remain there at rest because:

2. ConcepTest 4.1bNewton’s First Law II ConcepTest 4.1b Newton’s First Law II 1) more than its weight 2) equal to its weight 3) less than its weight but more than zero 4) depends on the speed of the puck 5) zero A hockey puck slides on ice at constant velocity. What is the net force acting on the puck?

3. 1) a net force acted on it 2) no net force acted on it 3) it remained at rest 4) it did not move, but only seemed to 5) gravity briefly stopped acting on it ConcepTest 4.1cNewton’s First Law III ConcepTest 4.1c Newton’s First Law III You put your book on the bus seat next to you. When the bus stops suddenly, the book slides forward off the seat. Why?

4. ConcepTest 4.1dNewton’s First Law IV ConcepTest 4.1d Newton’s First Law IV 1) the force pushing the stone forward finally stopped pushing on it 2) no net force acted on the stone 3) a net force acted on it all along 4) the stone simply “ran out of steam” 5) the stone has a natural tendency to be at rest You kick a smooth flat stone out on a frozen pond. The stone slides, slows down, and eventually stops. You conclude that:

5. ConcepTest 4.2aCart on Track I ConcepTest 4.2a Cart on Track I 1) slowly come to a stop 2) continue with constant acceleration 3) continue with decreasing acceleration 4) continue with constant velocity 5) immediately come to a stop Consider a cart on a horizontal frictionless table. Once the cart has been given a push and released, what will happen to the cart?

6. ConcepTest 4.2bCart on Track II ConcepTest 4.2b Cart on Track II We just decided that the cart continues with constant velocity. What would have to be done in order to have the cart continue with constant acceleration? 1) push the cart harder before release 2) push the cart longer before release 3) push the cart continuously 4) change the mass of the cart 5) it is impossible to do that

7. ConcepTest 4.3Truck on Frozen Lake ConcepTest 4.3 Truck on Frozen Lake A very large truck sits on a frozen lake. Assume there is no friction between the tires and the ice. A fly suddenly smashes against the front window. What will happen to the truck? 1) it is too heavy, so it just sits there 2) it moves backward at constant speed 3) it accelerates backward 4) it moves forward at constant speed 5) it accelerates forward

8. ConcepTest 4.4aOff to the Races I ConcepTest 4.4a Off to the Races I 1) 16 s 2) 8 s 3) 4 s 4) 2 s 5) 1 s From rest, we step on the gas of our Ferrari, providing a force F for 4 secs, speeding it up to a final speed v. If the applied force were only F, how long would it have to be applied to reach the same final speed? v F

9. From rest, we step on the gas of our Ferrari, providing a force F for 4 secs. During this time, the car moves 50 m. If the same force would be applied for 8 secs, how much would the car have traveled during this time? 1) 250 m 2) 200 m 3) 150 m 4) 100 m 5) 50 m ConcepTest 4.4bOff to the Races II ConcepTest 4.4b Off to the Races II v F

10. 1) 100 m 2) 50 m < x < 100 m 3) 50 m 4) 25 m < x < 50 m 5) 25 m We step on the brakes of our Ferrari, providing a force F for 4 secs. During this time, the car moves 25 m but does not stop. If the same force would be applied for 8 secs, how far would the car have traveled during this time? ConcepTest 4.4cOff to the Races III ConcepTest 4.4c Off to the Races III v F

11. 1) 200 km/hr 2) 100 km/hr 3) 90 km/hr 4) 70 km/hr 5) 50 km/hr From rest, we step on the gas of our Ferrari, providing a force F for 40 m, speeding it up to a final speed of 50 km/hr. If the same force would be applied for 80 m, what final speed would the car reach? ConcepTest 4.4dOff to the Races IV ConcepTest 4.4d Off to the Races IV v F

12. ConcepTest 4.5Force and Mass ConcepTest 4.5 Force and Mass 1) 4v 2) 2v 3) v 4) v 5) v A force F acts on mass M for a time interval T, giving it a final speed v. If the same force acts for the same time on a different mass 2M, what would be the final speed of the bigger mass?

13. A force F acts on mass m 1 giving acceleration a 1. The same force acts on a different mass m 2 giving acceleration a 2 = 2a 1. If m 1 and m 2 are glued together and the same force F acts on this combination, what is the resulting acceleration? F a1a1 m1m1 F m2m2 m1m1 a3a3 1) a 1 2) a 1 3) a 1 4) a 1 5) a 1 F a 2 = 2a 1 m2m2 ConcepTest 4.6Force and Two Masses ConcepTest 4.6 Force and Two Masses

14. ConcepTest 4.7aGravity and Weight I ConcepTest 4.7a Gravity and Weight I 1) F g is greater on the feather 2) F g is greater on the stone 3) F g is zero on both due to vacuum 4) F g is equal on both always 5) F g is zero on both always What can you say about the force of gravity F g acting on a stone and a feather?

15. 1) it is greater on the feather 2) it is greater on the stone 3) it is zero on both due to vacuum 4) it is equal on both always 5) it is zero on both always What can you say about the acceleration of gravity acting on the stone and the feather? ConcepTest 4.7bGravity and Weight II ConcepTest 4.7b Gravity and Weight II

16. ConcepTest 4.8On the Moon ConcepTest 4.8 On the Moon An astronaut on Earth kicks a bowling ball and hurts his foot. A year later, the same astronaut kicks a bowling ball on the Moon with the same force. His foot hurts... 1) more 2) less 3) the same Ouch!

17. ConcepTest 4.9aGoing Up I ConcepTest 4.9a Going Up I A block of mass m rests on the floor of an elevator that is moving upward at constant speed. What is the relationship between the force due to gravity and the normal force on the block? 1) N > mg 2) N = mg 3) N < mg (but not zero) 4) N = 0 5) depends on the size of the elevator m v

18. A block of mass m rests on the floor of an elevator that is accelerating upward. What is the relationship between the force due to gravity and the normal force on the block? 1) N > mg 2) N = mg 3) N < mg (but not zero) 4) N = 0 5) depends on the size of the elevator ConcepTest 4.9bGoing Up II ConcepTest 4.9b Going Up II m a

19. ConcepTest 4.10Normal Force ConcepTest 4.10 Normal Force Case 1 Case 2 Below you see two cases: a physics student pulling or pushing a sled with a force F that is applied at an angle . In which case is the normal force greater? 1) case 1 2) case 2 3) it’s the same for both 4) depends on the magnitude of the force F 5) depends on the ice surface

20. ConcepTest 4.11On an Incline ConcepTest 4.11 On an Incline 1) case A 2) case B 3) both the same (N = mg) 4) both the same (0 < N < mg) 5) both the same (N = 0) Consider two identical blocks, one resting on a flat surface and the other resting on an incline. For which case is the normal force greater?

21. ConcepTest 4.12Climbing the Rope ConcepTest 4.12 Climbing the Rope When you climb up a rope, the first thing you do is pull down on the rope. How do you manage to go up the rope by doing that?? 1) this slows your initial velocity, which is already upward 2) you don’t go up, you’re too heavy 3) you’re not really pulling down—it just seems that way 4) the rope actually pulls you up 5) you are pulling the ceiling down

22. F F 12 F F 21 1) 1) the bowling ball exerts a greater force on the Ping-Pong ball 2) 2) the Ping-Pong ball exerts a greater force on the bowling ball 3) t 3) the forces are equal 4) t 4) the forces are zero because they cancel out 5) there are actually no forces at all ConcepTest 4.13aBowling vs. Ping-Pong I ConcepTest 4.13a Bowling vs. Ping-Pong I In outer space, a bowling ball and a Ping-Pong ball attract each other due to gravitational forces. How do the magnitudes of these attractive forces compare?

23. In outer space, gravitational forces exerted by a bowling ball and a Ping-Pong ball on each other are equal and opposite. How do their accelerations compare? 1) 1) they do not accelerate because they are weightless 2) 2) accelerations are equal, but not opposite 3) 3) accelerations are opposite, but bigger for the bowling ball 4) 4) accelerations are opposite, but bigger for the Ping-Pong ball 5) accelerations are equal and opposite ConcepTest 4.13bBowling vs. Ping-Pong II ConcepTest 4.13b Bowling vs. Ping-Pong II F F 12 F F 21

24. ConcepTest 4.14aCollision Course I ConcepTest 4.14a Collision Course I A small car collides with a large truck. Which experiences the greater impact force? 1) the car 2) the truck 3) both the same 4) it depends on the velocity of each 5) it depends on the mass of each

25. 1) the car 2) the truck 3) both the same 4) it depends on the velocity of each 5) it depends on the mass of each In the collision between the car and the truck, which has the greater acceleration? ConcepTest 4.14bCollision Course II ConcepTest 4.14b Collision Course II

26. ConcepTest 4.15aContact Force I ConcepTest 4.15a Contact Force I If you push with force F on either the heavy box (m 1 ) or the light box (m 2 ), in which of the two cases below is the contact force between the two boxes larger? 1) case A 2) case B 3) same in both cases F m2m2m2m2 m1m1m1m1A F m2m2m2m2 m1m1m1m1B

27. ConcepTest 4.15bContact Force II ConcepTest 4.15b Contact Force II2m m F Two blocks of masses 2m and m are in contact on a horizontal frictionless surface. If a force F is applied to mass 2m, what is the force on mass m ? 1) 2F 2) F 3) F 4) F 5) F

28. ConcepTest 4.16aTension I ConcepTest 4.16a Tension I 1) 0 N 2) 50 N 3) 100 N 4) 150 N 5) 200 N You tie a rope to a tree and you pull on the rope with a force of 100 N. What is the tension in the rope?

29. 1) 0 N 2) 50 N 3) 100 N 4) 150 N 5) 200 N Two tug-of-war opponents each pull with a force of 100 N on opposite ends of a rope. What is the tension in the rope? ConcepTest 4.16bTension II ConcepTest 4.16b Tension II

30. 1) you and your friend each pull on opposite ends of the rope 2) tie the rope to a tree, and you both pull from the same end 3) it doesn’t matter—both of the above are equivalent 4) get a large dog to bite the rope You and a friend can each pull with a force of 20 N. If you want to rip a rope in half, what is the best way? ConcepTest 4.16cTension III ConcepTest 4.16c Tension III